Common mechanical torque wrenches, such as mechanical click-type torque wrenches, generally include an elongated tubular lever arm coupled at one end to a head adapted to engage a workpiece and a handle at the other end. A “click” mechanism includes a spring-loaded cam disposed within the tube and biased toward a secondary arm. A pawl or trip block is seated between the secondary arm and cam in recesses formed in the facing ends of the secondary arm and cam. The spring force drives the cam axially against the pawl to hold the cam aligned with the secondary arm until an applied torque overcomes the spring force and causes the cam to shift rearwardly in the tube away from the secondary arm. When this happens a pivot arm of the head contacts an interior of the tube creating a tactile “click.” When the torque is released, the spring causes the components to shift back to their original positions.
These common mechanical torque wrenches tend to excessively wear the cam, pawl, secondary arm, and tube interior due to their frictional interaction with one another. Current attempts at reducing this wear include using expensive specialty steel materials and heat treating. For example, it is known to construct the tube of ST52.3 steel and hardening via heat treating to 48-52 on a Rockwell C hardness scale (RC), construct the cam of a specialized powdered metal FC-0208-80HT and heat treating to 62 RC, construct the pawl of a specialized powdered metal FN-0208-105HT and heat treating to 62 RC, and construct the secondary arm of AISI 4140 steel and heat treating to 42-48 RC, in order to reduce wear and increase longevity. However, hardening of the components through the use of heat treating can cause distortion and degrade the surface finish of the components. This surface finish damage and distortion may require secondary processing operations to be performed, which add time and cost to the manufacturing process.